Currently, portable 3C (Computer, Consumer Electronics, Communication) products, such as personal digital assistants (PDAs), global positioning system (GPS), digital cameras, etc., have play an important role in modern life. These products typically use flat panel displays, such as liquid crystal displays (LCD), plasma displays or organic light emitting diode (OLED) displays, serving as the display medium for displaying images. OLED displays are characterized by features of high brightness, low power consumption, high contrast, high speed and low driving voltage.
An OLED display has a panel with multi-layers structure including a first electrode layer, a hole-injection layer, a hole-transport layer, a light-emitting layer, an electron-transport layer, an electron-injection layer and a second electrode layer stacked in sequence. In order to improve the light extraction efficiency of the OLED panel, at least one of the first electrode layer and the second electrode layer may be made by a patterned metal layer. However, since the metal layer has high reflectivity, thus most of the external light incident from the front of the display may be reflected by the metal layer, and an overall reduction in contrast may occur due to the perfect reflection of the metal layer. As a result, the display image quality of the OLED display may be deteriorated drastically, when the OLED display is operated in a circumstance with high background luminance.